Cochliones A-D, four new tetrahydrochromanone derivatives from endophytic Cochliobolus sp.

Four new tetrahydrochromanone derivatives, cochliones A-D (1-4), along with three known metabolites, 4-hydroxybenzaldehyde (5), 4-hydroxy-3-(3-methylbut-2-enyl) benzoic acid (6), and 2,2-dimethyl-2H-chromene-6-carboxylic acid (7), were characterized from the culture of Cochliobolus sp. IFB-E039, a fungus that resides inside the healthy root of Cynodon dactylon (Gramineae). The structures of 1-4 were accommodated by their spectral data (UV, IR, CD, HR-ESI-MS, (1)H and (13)C NMR, (1)H-(1)H COSY, HMQC, HMBC, and NOESY). The bioassay for the cytotoxic metabolite showed that cochlione C (3) inhibited human breast adenocarcinoma cell line (MCF-7) and human chronic myeloid leukemia cell line (K562) with IC(50) values of 21.99 and 4.59 microg/ml, respectively.